How to correctly map random texture to an object?
Once unwrapped your mesh, go to the UV Editor and enlarge, rotate, the mesh to achieve what you're looking for.
Is easier this way, but also you can do the same on the Node editor with a:
"Texture cordinate" plugged into a "Mapping" plugged into the "image texture" which contains the image you're using.

Steps:

(in the node editor) Add a texture cordinate and mapping tab

Connect the UV slot of the Texture Cordinate into the Mapping

Then, plug the mapping into "Image Texture" node which contains the image you're using.

Now, tweak the rotation and size on the Mapping tab to achieve what you're looking for.

I hope this works for you.